PeneloPET v3.0, an improved multiplatform PET Simulator

PeneloPET is a Monte Carlo simulation tool for positron emission tomography based on PENELOPE. It was developed by the Nuclear Physics Group at University Complutense of Madrid and its initial version was released in 2009. In this work, we present PeneloPET v3.0, which is now available precompiled for Microsoft Windows, MacOS and Linux OS. This new release includes improved simulations of the positron range in different materials and an accurate description of the decay cascades for many radioactive nuclei including the most common non-pure positron emitters used in PET. This enables the simulation of PET acquisitions with positron-gamma emitters. This release also includes many different fully-working examples, of both clinical and preclinical scanners, as well as several numerical phantoms. Due to the simplicity of the input the output files, and the installation process, PeneloPET v3.0 can be perfectly used not only for research, but also as an educational tool in class

Detailed spectroscopy of doubly magic Sn-132

The structure of the doubly magic Sn-132(50)82 has been investigated at the ISOLDE facility at CERN, populated both by the beta(-) decay of In-132 and beta(-)-delayed neutron emission of In-133. The level scheme of Sn-13(2) is greatly expanded with the addition of 68 gamma transitions and 17 levels observed for the first time in the beta decay. The information on the excited structure is completed by new gamma transitions and states populated in the beta-n decay of In-133. Improved delayed neutron emission probabilities are obtained both for In-132 and In-133. Level lifetimes are measured via the advanced time-delayed beta gamma gamma(t) fast-timing method. An interpretation of the level structure is given based on the experimental findings and the particle-hole configurations arising from core excitations both from the N = 82 and Z = 50 shells, leading to positive- and negative-parity particle-hole multiplets. The experimental information provides new data to challenge the theoretical description of Sn-132

Desarrollo de una nueva generación de técnicas de imagen PET

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 15-03-2022Positron Emission Tomography (PET) [Cherry et al., 2012] is a branch of nuclear medicine in which b+ radiation is used to provide valuable information on physiological processes in the body. Since the first commercially available scanner was developed in 1978 [Phelps et al., 1977], important advances have been made in the technique to improve the image quality. As a result, the amount and complexity of data generatedby new generations of PET scanners have drastically increased, requiring more computational power to keep the clinical workflow at reasonable duration, as well as improved models to make use of the increased resolution and improving corrections. In this thesis, we have tackled the current needs with the development of different tools for PET image reconstruction and simulation on the basis of speed, flexibility, and accuracy. All the software and methods presented in this work have been accelerate dwith parallel computing on the graphical processing units (GPU), and they have been designed to adapt to any scanner design. In the following, we present a summary of every chapter of this thesis...La Tomografía por Emisión de Positrones (PET) [Cherry et al., 2012] es una rama dela medicina nuclear en la que la radiación b+ se utiliza para obtener valiosa información sobre procesos fisiológicos en el organismo. Desde que el primer escáner PET comercial fuera desarrollado en 1978 [Phelps et al., 1977], se han hecho importantes avances en la técnica para mejorar la calidad de imagen. Como resultado, la cantidad y complejidad de los datos generados por las nuevas generaciones de escáneres PET ha aumentado drásticamente, requiriendo de una mayor capacidad computacional para poder mantenerlos protocolos clínicos en tiempos razonables, así como de modelos mejorados para aprovechar el aumento en resolución y mejorar correcciones en los datos. En esta tesis hemos abordado las necesidades actuales del PET con el desarrollo de herramientas de reconstrucción y simulación PET, fundamentadas en la búsqueda de velocidad, flexibilidad, y precisión. Todos los software y métodos presentados han sido acelerados por medio de GPUs, y han sido diseñados para adaptarse al diseño de cualquier escáner. A continuación, presentamos un resumen de cada capítulo de esta tesis...Fac. de Ciencias FísicasTRUEunpu

Real-Time 3D PET Image with Pseudoinverse Reconstruction

Real-time positron emission tomography (PET) may provide information from first-shot images, enable PET-guided biopsies, and allow awake animal studies. Fully-3D iterative reconstructions yield the best images in PET, but they are too slow for real-time imaging. Analytical methods such as Fourier back projection (FBP) are very fast, but yield images of poor quality with artifacts due to noise or data incompleteness. In this work, an image reconstruction based on the pseudoinverse of the system response matrix (SRM) is presented. w. To implement the pseudoinverse method, the reconstruction problem is separated into two stages. First, the axial part of the SRM is pseudo-inverted (PINV) to rebin the 3D data into 2D datasets. Then, the resulting 2D slices can be reconstructed with analytical methods or by applying the pseudoinverse algorithm again. The proposed two-step PINV reconstruction yielded good-quality images at a rate of several frames per second, compatible with real time applications. Furthermore, extremely fast direct PINV reconstruction of projections of the 3D image collapsed along specific directions can be implemented.Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEpu

First β-decay spectroscopy of In-135 and new β-decay branches of In-134

The beta decay of the neutron-rich In-134 and In-135 was investigated experimentally in order to provide new insights into the nuclear structure of the tin isotopes with magic proton number Z = 50 above the N = 82 shell. The beta-delayed gamma-ray spectroscopy measurement was performed at the ISOLDE facility at CERN, where indium isotopes were selectively laser-ionized and on-line mass separated. Three beta-decay branches of In-134 were established, two of which were observed for the first time. Population of neutron-unbound states decaying via gamma rays was identified in the two daughter nuclei of In-134, Sn-134 and Sn-133, at excitation energies exceeding the neutron separation energy by 1 MeV. The beta-delayed one-and two-neutron emission branching ratios of In-134 were determined and compared with theoretical calculations. The beta-delayed one-neutron decay was observed to be dominant beta-decay branch of In-134 even though the Gamow-Teller resonance is located substantially above the two-neutron separation energy of Sn-134. Transitions following the beta decay of In-135 are reported for the first time, including gamma rays tentatively attributed to Sn-135. In total, six new levels were identified in Sn-134 on the basis of the beta gamma gamma coincidences observed in the In-134 and In-135 beta decays. A transition that might be a candidate for deexciting the missing neutron single-particle 13/2(+) state in Sn-133 was observed in both beta decays and its assignment is discussed. Experimental level schemes of Sn-134 and Sn-135 are compared with shell-model predictions. Using the fast timing technique, half-lives of the 2(+), 4(+), and 6(+) levels in Sn-134 were determined. From the lifetime of the 4(+) state measured for the first time, an unexpectedly large B(E2; 4(+) -> 2(+)) transition strength was deduced, which is not reproduced by the shell-model calculations

Multicomponent Approach for Stable Methylammonium-Free Tin–Lead Perovskite Solar Cells

Mixed tin–lead perovskites suffer from several degradation pathways that hinder their effective implementation in tandem photovoltaic technologies. The main challenge involves removing the thermally unstable methylammonium cation from the perovskite composition and simultaneously increasing the oxidation resistance of the tin-based material. This study employs a multicomponent approach to address these issues, developing methylammonium-free tin–lead perovskite solar cells with improved efficiency and stability. The incorporation of cations that tune precursor solution properties enhances the quality of MA-free perovskite films, while reducing agents and surface engineering techniques enhance robustness and carrier dynamics. Consequently, the methylammonium-free perovskite solar cells achieve over 22% efficiency and demonstrate significantly enhanced stability, with minimal losses after over 700 h of continuous operation under 1 sun illumination. This work evidences the potential of comprehensive strategies to process fragile materials, such as tin-containing perovskites, with improved quality and brings them closer to successful broad applications